#include <bits/stdc++.h>

#define eb emplace_back
#define ep emplace
#define fi first
#define se second
#define in read<int>()
#define lin read<ll>()
#define rep(i, x, y) for(int i = (x); i <= (y); i++)
#define per(i, x, y) for(int i = (x); i >= (y); i--)

using namespace std;

using ll = long long;
using db = double;
using pii = pair < int, int >;
using vec = vector < int >;
using veg = vector < pii >;

template < typename T > T read() {
	T x = 0; bool f = 0; char ch = getchar();
	while(!isdigit(ch)) f |= ch == '-', ch = getchar();
	while(isdigit(ch)) x = x * 10 + (ch ^ 48), ch = getchar();
	return f ? -x : x;
}

template < typename T > void chkmax(T &x, const T &y) { x = x > y ? x : y; }
template < typename T > void chkmin(T &x, const T &y) { x = x < y ? x : y; }

const int N = 1e6 + 10;

int n, k;
char s[N];

bool check(int mid) {
	int cnt = 0;
	rep(i, 1, n) {
		if(s[i] == '1') {
			cnt += 1;
			i += mid - 1;
		}
	} return cnt <= k;
}

void solve() {
	n = in, k = in;
	scanf("%s", s + 1);
	int l = 1, r = n;
	while(l <= r) {
		int mid = l + r >> 1;
		if(check(mid)) r = mid - 1;
		else l = mid + 1;
	} printf("%d\n", l);
}

int main() {
#ifdef YJR_2333_TEST
	freopen("1.in", "r", stdin);
#endif
	for(int T = in; T; T--) solve(); return 0;
}
